Intraspecific variations in morphology of swamp barb (Puntius brevis)

Understanding inter-population variation and sexual differences in morphology is a fundamental part of taxonomic and biological research. External morphology of swamp barb (Puntius brevis) was compared between sexes and among three populations in the Mekong Delta, including O Mon-Can Tho (n=86), U Minh Thuong-Kien Giang (n=49) and U Minh Ha-Ca Mau (n=77). The results illustrate that color and countable parameters are similar in all populations. Nonetheless, 9 out of 20 morphometric indices are significantly different among three populations (P<0.05), where 6 indices are more important criteria to distinguish among swamp barb populations. Furthermore, the sexual dimorphism of this species is indicated in 16/20 morphometric indices consisting of 5 indices relating egg-carrying characteristics. In particular, the females have higher values of indices relating to abdomen and head parts while most of fin length indices are larger in males than in females. In sum, intraspecific variation in morphometrics of swamp barb is mainly due to sexual dimorphism rather than populations.

Complex sexually dimorphic traits shape the parallel evolution of a novel reproductive strategy in Sulawesi ricefishes (Adrianichthyidae)

Background Pelvic brooding is a form of uni-parental care, and likely evolved in parallel in two lineages of Sulawesi ricefishes. Contrary to all other ricefishes, females of pelvic brooding species do not deposit eggs at a substrate (transfer brooding), but carry them until the fry hatches. We assume that modifications reducing the costs of egg carrying are beneficial for pelvic brooding females, but likely disadvantageous in conspecific males, which might be resolved by the evolution of sexual dimorphism via sexual antagonistic selection. Thus we hypothesize that the evolution of pelvic brooding gave rise to female-specific skeletal adaptations that are shared by both pelvic brooding lineages, but are absent in conspecific males and transfer brooding species. To tackle this, we combine 3D-imaging and morphometrics to analyze skeletal adaptations to pelvic brooding. Results The morphology of skeletal traits correlated with sex and brooding strategy across seven ricefish species. Pelvic brooding females have short ribs caudal of the pelvic girdle forming a ventral concavity and clearly elongated and thickened pelvic fins compared to both sexes of transfer brooding species. The ventral concavity limits the body cavity volume in female pelvic brooders. Thus body volumes are smaller compared to males in pelvic brooding species, a pattern sharply contrasted by transfer brooding species. Conclusions We showed in a comparative framework that highly similar, sexually dimorphic traits evolved in parallel in both lineages of pelvic brooding ricefish species. Key traits, present in all pelvic brooding females, were absent or much less pronounced in conspecific males and both sexes of transfer brooding species, indicating that they are non-beneficial or even maladaptive for ricefishes not providing extended care. We assume that the combination of ventral concavity and robust, elongated fins reduces drag of brooding females and provides protection and stability to the egg cluster. Thus ricefishes are one of the rare examples where environmental factors rather than sexual selection shaped the evolution of sexually dimorphic skeletal adaptations.

The costs of being a good dad: egg-carrying and clutch size impair locomotor performance in male midwife toads (Alytes obstetricans)

Parental care is widespread across the animal kingdom. Parental behaviours are beneficial by increasing offspring survival but induce significant costs to the parents. Because parental care is far more common in females, the associated reproductive costs have been largely studied in this sex. Although male parental care is likely to involve significant costs, it has been markedly less well investigated. We studied the costs of egg-carrying on locomotor performance in an amphibian species (Alytes obstetricans) with male parental care. We examined complementary parameters including hopping performance, righting response, hindleg muscle response to egg burden, and homing time in males carrying or not carrying eggs. We found that carrying males showed altered locomotor performance for most traits. In addition, alteration of performance was closely related to relative clutch size. Clutch desertion occurred in smaller individuals carrying larger relative clutch mass, and performance after desertion was similar to that of non-reproductive individuals. Overall, our study demonstrates that carrying eggs significantly alters male mobility and that performance–clutch size trade-offs are relevant in understanding the evolution of paternal care.

Dispersal and migration have contrasting effects on butterfly flight morphology and reproduction

Movement may fundamentally alter morphology and reproductive states in insects. In long-distance migrants, reproductive diapause is associated with trade-offs between diverse life-history traits such as flight morphology and lifespan. However, many non-diapausing insects engage in shorter resource-driven dispersals. How diapause and other reproductive states alter flight morphology in migrating versus dispersing insects is poorly understood. To find out, we compared flight morphology in different reproductive states of multiple butterfly species. We found that dispersers consisted of ovulating females with higher egg loads compared with non-dispersing females. This trend was in stark contrast with that of migrating female butterflies in reproductive diapause, which made substantially higher investment in flight tissue compared with reproductively active, non-migrating females. Thus, long-distance migration and shorter resource-driven dispersals had contrasting effects on flight morphology and egg loads. By contrast, male flight morphology was not affected by dispersal, migration or associated reproductive states. Thus, dispersal and migration affected resource allocation in flight and reproductive tissue in a sex-specific manner across relatively mobile versus non-dispersing individuals of different species. These findings suggest that dispersals between fragmented habitats may put extra stress on egg-carrying females by increasing their flight burdens.

Does internal egg carrying impair foraging ability as much as external egg carrying in a neotropical spider?

Females not only produce costly gametes, but also store the eggs until oviposition, a period called pregnancy. The volume that eggs occupy in the female abdomen may decrease female foraging ability by making females slow. Although females of all species are subjected to these potential costs, it remains an unexplored matter in invertebrates. Females of the spider Paratrechalea ornata carry their egg sac after oviposition and thus represent a unique opportunity to evaluate pregnancy costs because females carry an extra volume before and after laying eggs. We conducted foraging ability experiments using P. ornata females on different treatments regarding pregnancy and maternal care. We first hypothesized that internal egg load and egg sac carrying decrease female foraging ability. We also hypothesized that greater egg sac size decreases female foraging ability. We found that both internal egg load and egg sac carrying decreased female foraging ability, and females about to oviposit had a similar foraging ability to females carrying an egg sac. Egg sac size did not influence female foraging ability. Our results show that pregnancy can impose high costs to female foraging ability, likely increasing their mortality during this period. The little support for our second hypothesis may also suggest that the decrease in foraging ability is not due to the volume being carried per se, but possibly an associated physiological state.

Kerevit (Astacus leptodactylus) Yemine Katılan Selenyumun Paraoksonaz ve Arilesteraz Enzim Aktivitelerine Etkisi

In this study, the effects of selenium added to the diets of Astacus leptodactylus at different ratios on paraoxonase (PON) and arylesterase enzyme activities (ARE) in the hepatopancreas and gonad tissues were investigated. In this study, control (K), trial 1 (D1), trial 2 (D2) and trial 3 (D3) were prepared at the selenium levels of 0,3, 0,6, 0,9 and 1,2 mg/kg, respectively. The crude protein and total energy levels of experimental diets were equalized. 12 ponds in 2 × 2 × 1 m dimensions were used. 75 female and 25 male crayfish were stocked in each pond (totally 1200 crayfish). This study was carried out in triplicate. The crayfish were fed twice a day during 9 months. PON and ARE enzyme activities were investigated in the tissue samples taken monthly from the crayfish. During the trial, significant differences were observed in the PON and ARE enzyme activities in the hepatopancreas and gonad tissues. The PON and ARE enzyme activities increased statistically significant in the crayfish tissues during the breeding season and incubation period. This increase was found to be statistically different in the D1, D2 and D3 groups compared to the control group. In conclusion, selenium had positive effects on PON and ARE enzyme activities of A.leptodactylus during its mating, pleopodal egg laying and pleopodal egg carrying periods.

Gravid females of Cephalcia chuxiongica (Hymenoptera, Pamphiliidae) are attracted to egg-carrying needles of Pinus yunnanensis

Cephalciachuxiongica Xiao is one of the most dangerous defoliators of Pinusyunnanensis and other pine species in Yunnan province, resulting in serious losses. Its distinguishing characteristics are the females’ aggregation oviposition and larvae’s aggregation feeding. In order to explore the mechanism of aggregation oviposition in this sawfly, preliminary olfactory bioassay was conducted in laboratory. In in-cage choice tests, on average vast majority gravid females selected the shoots that had been loaded and oviposited by a ‘pioneer’ female. In one-choice tests in laboratory by a Y-tube olfactometer, the gravid females were attracted by the odors of eggs-carrying shoots (PE), shoots with one delivering female and her eggs (PGE), needles’ extract (NE), and fresh eggs’ eluent (EL); the virgin females were attracted by odors of fresh needles (P), PE, PGE, and NE, but repelled by odors of virgin and gravid females. In two-choice tests, the odors were tested in pairs for gravid females. When compared with odors of gravid females (G) or P, gravid females showed significantly more tendency to odors of PE or PGE. When given odors EL vs. NE, gravid females preferred the odors of NE, but they did not make obvious selection between G vs. P, and PE vs. PGE. Based on the results, our conjectures were: (1) Delivery female, as a pioneer, can summon her conspecific gravid females to aggregate in the same pine shoot; (2) Pine needles’ odors were attractive for both the virgin and gravid females; (3) Gravid females could be attracted by odors released by the pioneer gravid females; (4) The olfactory sensation of the females may be changed by mating.